Distribution of Soil Phosphorus Fractions as a Function of Long-Term Soil Tillage and Phosphate Fertilization Management

Abstract

The forms in which phosphorus (P) accumulates in soils are dependent on management practices, fertilizer sources, and methods of application, which may promote distinct P solubility and plant uptake. We aimed here to evaluate how soil tillage and phosphate fertilization strategies affected soil P fractions over 17 years and to identify best management practices for improving labile P fractions. The experiment was conducted in a very clayey Rhodic Ferralsol (Oxisol) with initially very low P availability, during 17 years under soybean and corn, fertilized with 35 kg P ha −1 year −1. Treatments were two soil management systems (CT-conventional tillage and NT-no-till) and four phosphate fertilization strategies (TSP-triple superphosphate or RRP-reactive rock phosphate, applied to the crop furrow or broadcast). Soil samples were taken at five depth layers, and organic (Po), inorganic (Pi), and total P (Pt) were determined by Hedley's sequential fractionation. CT resulted in a more homogeneous distribution of Pi fractions throughout the soil profile, while under NT there was a steep depth gradient characterized by Pi accumulation in the fertilizer application zone. NT resulted in accumulation of Pi in more labile fractions and higher accumulation of Po physically protected by aggregation, both compared to CT. Also, under NT with RRP, there was a great accumulation of Pi associated with calcium (HCl Pi) compared to TSP, especially when the fertilizer was broadcast applied. An accumulation of Po down to 20 cm (CT) and 10 cm (NT) was also detected, compared to Cerrado natural soil. NT and RRP positively affected legacy P fractions and can be recommended as strategies to improve P fertilizer use efficiency.

Root phenotypes as modulators of microbial microhabitats

“…As nutrients and water availability are not evenly distributed throughout the soil profile, root architecture influences the ability of plants to exploit these resources, with implications for plant health, status, and performance (Lynch, 2019). Root architecture also indirectly influences water and nutrient availability in microbial microhabitats (Jobbaǵy and Jackson, 2001;Nunes et al, 2020), with implications for microbiome assembly (Hartman and Tringe, 2019). In this section, we discuss aspects of root architecture based on root spatial distribution, as less is known about plant root temporal dynamics and their influence on the rhizosphere microbiome (Fierer et al, 2010); even though studies of rhizosphere dynamics through plant developmental stages, can represent indirect assessments of root temporal dynamics (Edwards et al, 2018;Dibner et al, 2021;Xiong et al, 2021).…”

How withdrawing arable land affected the productive capacity of Haplic Kastanozems after 19 years of fallowing in dry steppes of the Ural piedmont

“…In dry steppe conditions, the uptake of phosphorus compounds depends on the availability of water and air to the soil, the content of other elements, plant characteristics and other factors. The profile distribution of P accumulation is related to the rock source of the soil parent materials, the degree of the profile development, past fertilization, and removals of soil materials by erosion (Nunes et al 2020;Alewell et al 2020). Table 5 presents the results of soil P in the studied soils.…”

“…In addition, greater root growth may contribute to a P increase in the arable layer (Motta et al 2002). Nunes et al (2020) found that less disturbed soil contributed to accumulation of more labile forms of phosphorus compared to conventional soil tillage.…”

Intercropping of Leguminous and Non-Leguminous Desert Plant Species Does Not Facilitate Phosphorus Mineralization and Plant Nutrition

“…As mentioned above, inorganic P has low mobility in the soil and most soils are P-deficient, especially in desert ecosystems, given that the most P present in soil is not directly available for plants [26]. Many studies have shown that active soil P is considered the most accurate indicator of soil-plant-P relations [27]. For instance, dissolved P turns over in seconds into labile P (resin P and NaHCO 3 -P), which is thought to supply the short-term P demands of plants.…”